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Found 97 results

  1. Hi, I have bought a new meade 8" dob (as in the pic ) and i have the skywatcher 130P goto scope. I was wondering what you pro's think of either of these 2 scopes and also give me an idea of how much better my results will be when using the bigger scope? my guess is that the bigger scope lets in more light and therefore I will get a clearer brighter image with more colour? note that I have to wait for delivery of the dob and i am very exited about it, also at christmas I am going to get some 20x80 bins (celestron sky master) and im looking forward to that to (this is because i found andromeda galaxy in a cheap pair if 10x50 bins and i was a bit disappointed with the result, I dont have a decent pair of bins yet). so, what do you thing of the 8" dob? thanks in advance.
  2. The Newtonian telescope design is both simple and remarkable. It is capable of producing a perfect image on axis, but off axis, the image quality degrades mainly due to an optical aberration called coma. Modern fast Newtonians and Donsonians of F/5 and below have a surprisingly small diffraction limited spot (just 2mm across in an F/4.5), where the image is not disturbed by coma. The Astro-Tech (also sold under the Altair Astro and GSO brand labels) coma corrector has been designed to cancel out this aberration to give a flat, wide field with high resolution from edge to edge. It is manufactured by Guan Sheng Optical (GSO) and was developed by Astro-Tech from a high quality, modern optical design by Roger Ceragioli My corrector came in a nice box and consists of two parts, the coma corrector itself and a 2" eyepiece adaptor which screw together with a 48mm (2" filter) thread. The eyepiece adaptor has two screws and a brass compression ring and is marked ALTAIR ASTRO 2", Coma Corrector, Made in Taiwan. At least I knew I had the right part, but no other documentation was supplied and I had to search the web for information on how to use it. Unfortunately the corrector is not ready for visual use as supplied, because of inadequate eyepiece spacing. The proper spacing is not critical and a compromise spacing to cover your eyepieces can made up with 2" extender tubes, such Hyperion fine tuning rings or empty 2" filters. You do not need a turntable like that of the Tele Vue Paracorr. With the spacers installed, the assembly which is now about 70mm long just slides into the focuser tube like a barlow. In this arrangement the focal point is moved in by a small distance of about 10mm (see photographs below). The corrector acts as a very slight barlow, enlarging the image by just about 10%. The lenses are nicely coated and reflect pale green. The aluminium housing is cleanly finished in satin black and the combined unit weighs about 350 grams. Once set up properly in a collimated telescope, the corrector works just as you would expect to give a clean, flat image. The view feels quite different, much more like a refractor, with pin point stars from edge to edge, but no chromatic aberration. Objects can be allowed to drift across the view of wide angle eyepieces with little or no visible loss of sharpness. The removal of coma can be clearly demonstrated by doing a star test on and off axis without the corrector installed and then with it. Any loss of contrast due to the extra corrector glass (two doublet lenses) in the light path is undetectable, I think. The coma corrector is now a permanent fixture in my focuser except on occasion when viewing planets with my 200mm Newtonian which now has a motor drive. It seems to me that a coma corrector should be a standard accessory for all fast Newtonian telescopes and particularly for larger Dobsonians with no tracking. This model is an effective, affordable example and I strongly recommend it. The first issue is actually finding one in stock. Supply has been patchy over the years and at the time of writing, it is listed by Astronomics (Astro-Tech brand at $135, including T-mount, but out of stock), Agena (GSO brand at $130, including T-mount, but out of stock), Ian King (Altair Astro brand at £88) and Telescope Service (GSO brand without visual adaptor at 61 Euro). There is then the issue of setting it up properly and most of the remainder of this review is devoted to showing how this can be done, but first there is a little information about Newtonian telescopes and coma. Newtonian telescopes are all designed with a single figured mirror in the shape of a parabola rotated on its axis, a paraboloid. All mirrors of a given focal length are the same shape. If you have a fast mirror, it is easy to to create a slow one of the same focal length, just by blanking off the outer part of the mirror. It is the outer part of the mirror that generates coma, which is zero on axis but which increases linearly the further from the axis you get. At the focal surface, the amount of coma is independent of the mirror focal length so a single corrector will work for any Newtonian. In practice, a perfect corrector is not attainable so the designer will aim to produce the best result he can for a specific F/ ratio, F/4.5 for this model I understand. However, the corrector will give good results for mirrors that are somewhat faster than this and for all slower mirrors. Coma correctors would actually be better called Newtonian correctors, because the designer is looking to produce the smallest attainable spot size for a point source, so will also be looking to reduce the other lesser Newtonian aberrations, field curvature and astigmatism. To do this, he will have in mind a particular focal length, around the longest that is commonly used (so about 2000mm or slightly less), because these aberrations are less in longer telescopes and it is wise not to over correct significantly. Newtonian telescopes are perfect on axis, but coma damages image quality at even a modest distance off axis. At the focal plane, about 1mm off axis, in an uncorrected F/4.5 Newtonian, the image is just at the diffraction limit and the strehl of even a perfect mirror has fallen to 0.8. In a 250mm scope, this gives a coma free, sharp field of about 6 arc minutes across, about 1/5 of the apparent diameter of the moon. For comparison, the field stop of a 9mm orthoscopic eyepiece is about 6mm so only the central 1/3 (1/9 of the area) of the view is free of coma in an F/4.5 scope. Coma increases sharply with the speed of the telescope, at the focal surface inversely with the cube of the F ratio. Collimation is the business of lining up the coma free sweet spot with the centre of the eyepiece axis. The tolerance for collimation is perhaps 1/4 (though some would say 1/6) the size of the sweet spot so that it covers the centre of the eyepiece. So far as I can tell, this tolerance also looks good for a telescope fitted with a coma corrector. To set up the GSO coma corrector properly, the total back focus (distance from the last lens to the focal plane) has to be about 75mm. The designer says that it is not critical and from 65mm to 85mm will produce a good spot size. This distance will be made up somthing like mine below, added to the height of the eyepiece focal point height above the eyepiece shoulder (or subtracting the height below the shoulder). 1.25" My 2" 2mm 2mm Spacing from last coma corrector lens to the shoulder 45mm 45mm 2" adaptor spacing 11mm .... 2" to 1.25" adaptor (if any) 19mm 19mm Spacers (Hyperion 14mm ring + empty 2" filter) 77mm 66mm Total (excluding eyepiece distance) My one 2" eyepiece has a focal point above the shoulder, and my 1.25" eyepieces are all within -12mm/+8mm of nominal, so are all fine. Tele Vue is unique in publishing the height below the shoulder of the focal point for all their eyepieces. For other users, you are going to have assume the focal point is close to the shoulder or measure the position. First, locate the prime focus by taping a piece of tracing paper to the top of the focuser and focusing on something. This does not have to be at night and can anything sufficiently distant so that it comes into focus, such as a church spire or distant tree. It does not depend on the telescope so using a refractor with a graduated focus scale is very convenient. You then measure how far in (plus) or out (minus) you have to move the focuser for each of your eyepieces in turn. For users only intending to use 2" eyepieces, a single 28mm Hyperion tuning ring might be fine. If you do not like the idea of finding empty filter rings, or more likely buying cheap ones on eBay and removing the glass, some suppliers (in particular Telescope Service) have spacing rings with the right 48mm thread, in a few sizes such as 10mm and 20mm, but these are generally expensive. Variable spacers are also available but these are not going to sink into your focuser tube. When I first set this up I had to remove a 2" to 2" adapter to allow the unit to go all the way into the focus tube. This left too little out focus so I made a plastic washer (from a yoghurt tub, see photo below) to prevent the corrector slipping all the way into the focuser and providing the necesssary out focus. One correspondent who uses only 2" eyepieces has done away with the eyepiece adaptor and has simply added enough extender rings to screw the corrector to each eyepiece as he uses it. I hope that this will is enough information to set up this corrector properly but I would welcome questions, and of course comments and correction.
  3. Nadine2704

    Jupiter

    From the album: My (very amateurish) attempts at astrophotography!

    First attempt at Jupiter - not great, but it's a start! Canon 70d mounted to 8" Dobsonian at prime focus 30 sec video, stabilised in PIPP Stacked in Registax
  4. Looking at this scope as my first decent scope. Anyone know pros v cons?
  5. WOW! Had a great view! Used my Pocket Sky Atlas to plan the night, then I just shot right out there! Saw the 7 Sisters (Pleiades), then hopped to the Orion Nebula! Used my ES 18 mm to find it then switched to the Morpheus 12.5 mm and could actually see wispy parts of the Nebula! ( I guess that’s what it was! LoL!) Really amazing! Called the wife out to take a look. Next I want to find Andromeda! Greg
  6. Hi there, Jon from Montreal, just saying hi. Got my first REAL telescope today. Skywatcher Classic 200P Dobsonian 8". I say real cause the 2 other telescopes I've own have been bought at art store or toys r us. Unfortunately I have yet to use my new Dob' due to all this cloud cover, hopefully it will clear up at least for the weekend. If any one has any advice to give me, about eye pieces etc.. feel free to
  7. Hi, I bougth a skywatcher skyliner 200p (a newtonian dobsonian telescope) and I should receive it in 2 weeks. Since I know nothing yet of the practicalities of astronomy I wonder what accessories I should get initially for it if any. I would love to hear your advice. Collimation : From what I gathered, collimation seems a necessary thing to perform, even with new telescope, right? I read a lot of good and bad thing about laser and only good thing about cheshire. Since I ll be alone operating the telescope, which one should I get if any ? a cheshire like this one https://www.ebay.co.uk/itm/Ascension-1-25-Short-Cheshire-Collimation-Eyepiece-UK/322431518490?hash=item4b126a871a:g:VYkAAOSwWxNYrXEi or a laser (in which case which one would you recommend )? Any resources on how to perform collimation. That sounds a bit scary Finders: I heard a lot about telrad and I am considering one is a rigel quickfinder similar or better ? (https://www.firstlightoptics.com/finders/rigel-quikfinder-compact-reflex-sight.html) Can these be installed without hassle on my skywatcher ? I also heard that the default straight finder installed on the skywatcher is not very nice to use as you need to bend yourself (and the image is inverted) Should I get a right angle one like : https://www.firstlightoptics.com/finders/skywatcher-9x50-right-angled-erecting-finderscope.html How would I install it? Is it as simple as replacing the straight one ? precise finding In order to find objects in the sky, I though first to buy a push to telescope like the orion xt8i but because of the price, I decided to go with the simple skywatcher skyliner 200p. This now means I have to learn to navigate in the sky, which is probably a good thing anyway. Finders helps here but to be precise, I thought about "setting circles" and inclinationmeters but these would require some time to built it and attach it. What do you think? Any good resources ? Probably something I can reconsider later? I might instead try the "skeye" app (https://play.google.com/store/apps/details?id=com.lavadip.skeye) but I ll need to find a way to fix my phone on the telescope. Protection / care: Is there any precaution I should take when storing my telescope (while not in use)? Any useful accessories ? Filters: Since the moon is such easy target and fascinating on its own. should I get a moon filter ? What about planetary filter, are they worth it ? Any other thing I should consider getting ? Any recommended books ? Cheers Ronan
  8. I've been given a lovely Dobsonian, the balance isn't quite right, I need slightly more weight at the back, how do I alter the weight? Also, I need advice in collimating it, without a collimator, is there any other way to get it all sorted? Thanks in advance.
  9. Hello, after deciding on getting a dobsonian either a 150p or 200p I was wondering if anyone leaves their dobsonian outside?. Obviously I won’t be leaving it uncovered, I was hoping if there are any special all weather covers? So I can just leave it all assembled.I do have some room left in my garage but might be a tight fit . I was also thinking of getting a bag like this ( something a bit bigger) http://www.ikea.com/gb/en/products/textiles-rugs/outdoor-textiles/tosterö-storage-bag-for-cushions-black-art-20292328/?cid=gb|ps|pla||||. I’d wrap it up in dust sheets or something as well. I really want to get one of those dobs but I’m struggling on where I can store it. And please would someone confirm the weights for me Ive seen the 150p dob is about 7kg is and the 200p is about 9kg and the base being around 10kg for both is this correct?
  10. sorry for my bad english first xD Hello , snice i have no idea what to look for and i kinda want something for beginner i saw that used scope for around $150 at first looked really what im looking for ,but also i thought there may be something wrong and i just wanted to ask is this price okay for the scope and if not what can go wrong. The telescope is bought 2002 and it comes with Plossl 25mm ,moon filter , some bonus filter (idk xD) and MEADE Plossl 5 Element 20mm I saw the original scope in the box have 30mm 2" but snice the price is that low i dont really expected the 30mm Anyway the only thing that comes to my mind (im not telecope expert) is that maybe the cooling fan is missing and because of the DIY things on side of the scope.Please help xD if there's something more i should look for or if its bad scope at all ill just leave it ---- thank you in advice
  11. Hello folks, for long I have been browsing the internet to find a suitable 10in dob and despite lack of reviews, I have decided to take the plunge with the Bresser Messier 10in Dobsonian. There was some doubt at first, especially when considering the popularity of similar scopes from Skywatcher, Meade and GSO. Even though Bresser is relatively new to the market, it has some clever features: 1. The massive 2.5in hexagonal rack and pinion focuser is very solid and the movement is smooth. Despite being only single speed, Bresser sells an a dual speed 10:1 extension. However, I find the movement precise enough and do not need the extension at the moment. 2. Optical finder scope feels a bit cheap but it is a nice upgrade over the red dot finder I had on my previous scope. 3. Rocker box style base allows disassembling the scope into two pieces (OTA and base). 4. Tube rings allows the scope to be easily balanced when adding weight + after adding a suitable dovetail plate, the OTA can be used on an equatorial mount (if you plan to upgrade to an eq mount, I would consider the 8in model, as an eq mount for the 10in would be expensive). The only negative comments I can give about the scope is the production process. There were some minor issues with the assembly with the scope as parts did not fit properly. First problem was with one hole drilled deeper (loosening the particular screw fixed the issue). Another problem was with the altitude wheel as it made the OTA to pop out from the rocker box. (A loose screw on one of the plastic pads between the box and altitude wheels was causing this. Make sure all these screws are tightened and below the surface of the pads). Lastly, I assume there must have been a mistake in the quantity of items included (I got twice as many screws for the rockerbox and 2 eyepieces instead of one, both were 25mm super plossl but the standard was a 1.25in advertised on the bresser webpage, while the other was a 2in wide angle) I did not have the opportunity to test the scope outside properly due to clouds. Update: 01.06.2017 Had the chance to try it out on the moon and jupiter to a max magnification of around 160x. The results were very sharp and detailed views. Unfortunately, clouds rolled in before it got dark enough to observe DSO's. I am waiting for clouds to clear and a package with a 42mm wide angle eyepiece and a 2in GSO 2x ED barlow to arrive next week.
  12. Hi, I have been experiencing problems with sticky altitude positioning on my Lightbridge Dob. The bearings are basically an aluminium ring bearing on a felt base. I may have made it worse by adding weights to the scope. I have read that adding wax to the bearing helps but I am nervous that it is going to end up a sticky mess and worsen the problem. Does anyone have experience with swapping felt for teflon pads?
  13. Thought it was time to step into the light side for a while, especially with SGLXI coming up, so have let this prisoner out of his box. He's been holed up since October. If the forecast clear skies materialise tonight, I should be able to set the observatory rig going, then pop outside for a bit of a visual tour. Given the light pollution here, will stick to brighter targets, but interested to hear your suggestions for nice objects to view at this time of year. Cheers Tim
  14. Excellent condition Skywatcher 200p Dobsonian telescope, comes with Telrad attached. Also included are a couple of 10mm 20mm and 25 mm eyepieces and a lovely Olivon 8-24mm zoom lens. Selling as a compete package. One small issue with the focuser, the rubber on the focuser wheels has split so I have put a little black tape on to secure. This is purely cosmetic and doesn't affect the operation at all. £225 collected from Barnsley, South Yorkshire. REDUCED, need it gone so £200 collection only. Fixed price. Any questions please fire away.
  15. The appeal of a square box tube, in one length, is ease in construction, mounting the mirror cels, opening lid for access to inside, being able to switch to different FL optics if desired and the general simplicity of carpentry. Right angles rule! Can anyone with carpentry know-how, suggest a good wood, for a 5 foot long box-tube, that will not warp unbraced? Mirror size 12 inches upwards, so minimum 13 x 13 inches inside.
  16. I just ordered the SkyWatcher 200P Dobsonian from FLO this afternoon and after reading a lot of reviews on this model definitely believe I made the right choice ... Does anyone have any suggestions on the maximum ( or maybe " reasonable " would be a better word ) magnification for the planets , specifically Jupiter and Saturn ? So far with my Meade Infinity 600/90/f6.7 refractor and the 6.3mm kit lens I see both planets at around X95 magnification which shows the bands on Jupiter and that fainter , thinner band 2/3 up on Saturn ( anyone know what that one is called ? ) and also the moons too ... What has proved to be elusive so far is the famous red spot on Jupiter and also the Cassini division on Saturn's ring system ... Has anyone ever even tried the maximum magnification of X406 on the planets or would that be only really usable on the Moon . Any advice would be very appreciated .
  17. Hello, Am very new to this so apologies right from the start. I have recently just bought a skywatcher akyliner dobsonian 200p and i set it up. However the image is very blurry even when i remove all magnification and just look into the primary mirror eveything looks very blurry including the moon or nearby trees etc. I am unsure what the issue could be as i am eager to get started on my stargazing! Could someone please assist me or at the very least point me in the right direction. Kind regards
  18. Hi .I'm thinking of changing my finderscope on my 200p skyliner. Is it possible to fit a skywatcher st80.any information would be helpful to me.
  19. I'm scared I have attained the debilitating Collimation Syndrome ( HClV-1a : Human Collimation Virus strain 1a. - mild/severe). Was out with Calpernia yesterday (ehm..my scope's second name..) and I decided to correct her eyesight..again.. (She's now 11 month's old...her first name is Sky, her surname Watcher, 10" of joy..) I followed my baby's collimation guide (I mean Astrobaby..sorry..) And to my surprise the collicap worked (which I have never tried before) very well... I could see all the six mirror clips on my primary mirror..but it seemed like the clips were not evenly spaced with reference to the side of the secondary mirror's edge. As explained in AstroBaby's guide.. "The photograph to the left shows what the actual view should be like at this stage of the process. Note the three mirror clips are all visible and are all equally close to the edge of the secondary mirror and the secondary is showing round and centred to the focuser tube ( the dark area at the edges of the picture)." (Astrobaby, 19..) source: http://www.astro-baby.com/astro_baby_telescope_help_and_advice.htm. Collimation Guide for Newtonian Reflector Telescopes. I checked with my Cheshire...it showed that (according to the Cheshire) the secondary didn't appear quite cylindrical in the tube. So now I recollimated the whole thing...using my trusted Cheshire...and everything is bang on.. When I insert the colli cap thereafter I can see all the clips, almost all the same size, but still with a slight miscorrection of spacing around the secondary's edge.. Maybe I'm just getting old, and my eyes are tired..
  20. Just a few questions... Would I be right in assuming that there's a telescope made for a dobsonian mount, and then there's all other telescopes, never the twain shall meet (with an EQ mount)? How exactly is a dobsonian telescope attached to the mount? Are dobsonian telescopes always newtonian reflectors? If I have a well supported substantial garden table which is about 3' high and about the same across, what size dobsonian would be usable if just plonked on top of it? I assume they are meant for use on the ground, so it may not be possible to reach the eyepiece if it's stuck right at the top end of the tube, unless it's a particularly small dobsonian (or I'm looking at the horizon, which isn't going to happen from that location). As my usual observing location appears to have a trailer parked on it at the moment, just exploring other possibilities... Thanks for answering my silly questions!
  21. Hi, never posted in the imaging section before but heres a Moon shot taken on a 150p dob with a Nikon D300 at iso 800 1/320 second. Mirror lock up and timer delay. D300 was attached with a 2 x Barlow so had to take a piccie of the bottom and then the top half of the Moon as it was too big ( and no I couldn't have moved back a bit !) and then stitched in photoshop
  22. Hey folks, this is an attempt to image m45 and get the nebulosity of the "seven sisters". 20subs * 30sec on ISO 1600. enjoy, please free to comment and collaborate. theo
  23. I am building a newtonian reflector telescope, and I could use some help. This is my first DIY telescope, so I am pretty unprepared and don't know where to buy some stuff, namely optics. I am planning on going for a 8" aperture, but I can't find a website that sells mirrors. What website or sites has good quality mirrors but isn't to expensive, and what mirror coating is best? All help is appreciated, thank you in advance!
  24. In my struggles with finding someone who wants to head out to the desert to do some late night observing... I have taken to my back yard in LA.... Honestly I know these images are not anything compared to the things that people post here... but I am slowly working on adapting to the living xD And with taking the images with a cellphone camera... lol... I cant really complain... iPhone X Camera, 2x Barlow, 25mm Eyepiece... I know sad attempt... but planning my trip out to the desert for when the real camera gets here! If anyone has any advice for city observing... They would be very appreciated... I know that there is a filter that is designed to try to remove most of the city lights.... but I have no idea what its called.
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